Compression-pump for refrigerating apparatus.



N0. 640,9". Patented Ian. 9, 1900. G. B. HIETT.

COMPRESSION PUMP FOR REFRIGERATING APPARATUS.

A uwsi n fil ed June 12, 1897.) (No Model.) 2 Sheets-Sheet I wwme ooeoK/ A I N0. 640,9". Patented ]a.n. 9, I900.

a. s. HIETT. CUMPRESSION PUMP FOR REFRIGERATING APPARATUS (Applicationfiled June 12, 1897.)

2 Sheets-Sheet 2,

(No Model.) 7

GEORGE B. HIETT, OF ATLANTA, GEORGIA, ASSIGNOR OF ONE-HALE TO SAMUELLOUISBREWER, OF TUSKEGEE, ALABAMA.

COMPRESSION-PUMP FOR REFRIGERATING APPARATUS.

SPECIFICATION forming part of Letters Patent No. 640,911, dated January9, 1900. Application filed Tune 12. 1897. Serial No. 640,496. (N0model.)

To ctZZ whom it may concern:

Be it known that I, GEORGE E. HIETT, a citizen of the United States,residing at Atlanta, in the county of Fulton and State of Georgia, haveinvented certain new and useful Improvements in Compression-Pumps forRefrigerating and Ice-Making Apparatus, of which the following is aspecification, reference being had therein to the accompanying drawings.

This invention relates to improvements in compression-pumps,and isprimarily designed for use in connection with ammonia ice-makingmachines or refrigerating plants.

The object of the invention is to provide a pump of this character whichis adapted to receive and compress the refrigerating medium in a liquidor densely-saturated state and to be maintained thereby at a lowtemperature without the use of a water-jacket, to reduce friction of theparts to the minimum and provide for the ready discharge of the residuumfrom the cylinder-chamber, to provide a durable and efficientconstruction of valve mechanism for the piston and dischargevalvemechanism for the cylinder, and to generally improve and simplify theconstruction and render more efficient the operation of this class ofapparatus generally.

To this end the invention consists in the features and in theconstruction, arrangement, and combination of parts hereinafterdescribed, and particularly pointed out in the claims following thedescription, reference being had to the accompanying drawings, forming apart of this specification, wherein- Figure 1 is a vertical sectionalview of a compression-pump constructed in accordance with my invention.Fig. 2 is a sectional plan view of the stuffing-box and oil-receptaclethereof. Fig. 3 is a similar View of the pumppiston. Fig. 4 is a planview thereof. Fig. 5 is a vertical sectional View of a modified form ofpump-piston. Fig. 6 is a plan view thereof. Fig. 7 is a detail sectionalview of the bonnet and mechanism for controlling the oil-supply thereto.

Referring now more particularly to the drawings, wherein like referenceletters and characters designate corresponding parts throughout theseveral views, A represents the pump-cylinder, which is vertical andprovided in its outer side just below its upper head B with asuction-port in the form of a pipe B and at its lower end with adischargevalve chamber 0, having a discharge-port in the form of a pipe0. The piston-rod D has attached to its lower end a piston which worksdownwardly to compress and expel the ammonia and is constructed asfollows: A hollow piston-head shell E is provided at its upper end witha plurality of portsfand at its lower end is open and internallythreaded, and screwed in the open threaded end of the shell is avalve-seat f, in which is arranged a vertically-movable valve f Theupper end of the valve-seat is formed with a spider f which permits thefree and unobstructed passage therethrough of the ammonia gas andliquids, and supported by said spider above the valve-seat is aremovable cup f through which passes the valve-stem f A coiled spring fis wholly inclosed in said cup and about the valve-stem and abutsagainst a nut f engaging the upper end of said stem. This springoperates to normally hold the valve closed against its seat.Guide-fingers f are preferably formed on the upper side of the valve andoperate to insure the valve moving in a right line and properly seatingitself.

In Figs, 5 and 6 a modified construction of pump-piston is illustrated.As shown in said figures, the spider f is formed on the top of thehollow piston-head shell, and the pistonrod is attached directly theretoand is provided with a downwardly-projecting extension f about which iscoiled the spring f, which rests on a nut f tapped onto the lower end ofsaid extension. A hollow boss or cup f is fitted over the spring and atits lower end is bolted to the valve f, which in this case seatsagainsta seat formed directly in the bottom of the piston-head shell. Inboth con-' structions of piston-head the hollow boss or cup serves as ahousing to protect the spring from injury and prevent scale and otherresiduum from coming in contact therewith and interfering with itsaction, so that the proper operation of the valve is insured at alltimes, and the nut serves as a means whereby the tension of said springmay be regulated as desired.

The discharge-valve chamber or casiu g C on the lowerend of the cylindercomprises an an nular wall G,formed integrally with and hanging pendentfrom the detachable head H and forming a chamber or casing of the samediameter as the cylinder. This chamber is closed by a bottom plate E,bolted to an an.- nular flange h, formed on the lower end of said wall.In. this casing is arranged a vertically-movable balanced valve '5, thatcontrols a port 1" in thelower cylinder-head,which port is made ofconsiderably less diameter than the cylinder. As shown, this valve is ofconsiderable area to permit of the rapid passage of the ammonia-gas,but-is also of less diameter than the cylinder, and on its under side isprovided with a hollow stem j, that fits over a stud k, supported by thebottom plate- D. The sides of the valve are provided with ports'l, and acoiled spring m is arranged in the stem and rests on the stud. Thespring operates to-normally hold the valve closed, and the ports Zpermit the ammonia-gas to have access to the under side of the valve andprevent the formation of a vacuum thereunder. Guides 11. project fromthe bottom plate of the valve-casing and embrace the valvestem to insurethe proper movement of the valve, and by detaching said bottom plate thevalve can be removed and replaced when desired without disturbing any ofthe other parts of the pump. The discharge-port O is of the same area asthe outlet formed by the downward movement of the valve on the downstroke of the piston, which permits the ammonia gas and vapor to expandand relieve itself of a portion of the heat developed by compression.

It is essential to the operation of the pump in compressing the ammoniain a liquid or densely-saturated state that the suction and dischargeports, bottom chamber, and valves be of substantially the proportionsshown. The suction-port should be of some what larger area than thedischarge-port in order to allow for the difference in volume of theammonia before and after compression, while the valve in the piston-headshell should be of less diameter than the bore thereof, and thedischarge-valve of materially less diameter than the cylinder in orderto provide for the sensitive balancing action of said valves, as well asto prevent resistance to the free opening'of said discharge-valve by thepressure of the gas on the high-pressure side of the refrigeratingapparatus and the necessity of compressing the ammonia to an extremelyhigh temperature to force it through the port in the bottom head.

I am aware that it has heretofore been proposed to employ a pump forcompressing air comprising a cylinder having suctionand discharge portslocated, respectively, at its top and bottom, a valved piston tocompress the air on its'downstroke, and a valved dischargechamber, thevalve of the piston being approximately of the diameter of the bore ofthe head thereof and the valve of the dischargechamber of greaterdiameter than the cylinder and adapted to be opened by direct contact ofthe piston therewith. Such construction of pump could not, however, beemployed for compressing anhydrous ammoniain a humid or saturated state,because the dischargevalve being of larger diameter than the barrel ofthe cylinder contains more square inches on the bottom side than on thetop and is of so great an area that it would be held to its seat by thecondensing pressure on the highpressure side of the apparatus, thusrequiring a third more power to drive the piston against the valve toopen it, which would cause the compression and superheating of theammonia to an objectionable degree. To avoid this objection and to adaptthe pump for compressing ammonia in a liquid or saturated state, so thatit will pass into the discharge-valve chamber at a low temperature andnot be unduly expanded, I have contrived the construction herein shown,wherein the discharge-valved is of less diameter than the cylinder andis free of flat surfaces for the gas on the high-pressure side to actupon, whereby the valve is sensitively balanced and the piston on itsdischarge-stroke only increases the pressure in the cylinder to a pointslightly above that in the dischargechamber on the high-pressure side,by which superheating of the ammonia is obviated and the piston adaptedto be operated with the eX penditure of less power. I am thereby alsoenabled to avoid opening of the valve by direct contact of the pistontherewith and vibration and chattering of the valve under the action ofthe piston. I therefore do not claim,

broadly, a pump having a barrel or cylinder.

provided with suction and discharge ports located, respectively, at itsupper and lower ends with a piston working therein to compress the gason its downstroke, but a pump of this type having a novel construction,arrangement, and proportion of parts by which it is adapted to compressthe ammonia in a liquid or saturated state and to force it to thecondenser at a temperature but little above the boiling point.

Another important feature resulting from my construction is that thelower end of the cylinder is strengthened by a head of large dimensionsand the discharge-valve and its working parts are all supported by saidhead and adapted to be removed by detaching the head and without liftingor removing the cylinder-barrel itself.

Bolted onto the upper head of the pumpcylinder is a bonnet 0, throughwhich the piston-rod D passes. An outer stuffing-box be operated throughthe medium of a suitable tool to tighten or loosen the packing betweenthe piston-rod and top of the bonnet, while the gland oftheinnerstuffing-box has formed thereon or attached thereto a worm-wheelg, which is engaged by a worm-shaft 7', that at one end is provided witha fixed collar r, rotatably arranged in a recess r covered by a nut rfitted in the side of the bonnet, and at its other end projects througha stuffingbox r on the side of the bonnet. A handwheel 8 is fixed on theouter end of the wormshaft, by means of which said shaft may be rotated,and the gland thus turned to tighten or loosen the packing, as may bedesired, without the necessity of having access to the interior of thebonnet. The outer open side or end of the bonnet is tightly closed by aface-plate T, which may be readily removed at any time, however, when itis desired to repair or repack the internal stuffing-box or clean thebonnet. Fitted in the top of the bonnet is a hand-pump or force-feed cupu, by which oil is supplied to the bonnet, and this pump is providedwith a lateral nozzle 10, which is so arranged as to inject oil directlyupon the piston-rod and gland of the internal stuffing-box. A draw-offpipe "0, provided with a valve 1;, leads from the bottom of theoil-chamber to the exterior and serves as a means for removal of aportion or all of the oil when its level is too high for efficientworking and whenit is desired to get access to the bonnet. Theface-plate is provided with a sight-gage 10, whereby the height of oilin the chamber may be readily ascertained from the outside. By thisconstruction of parts the packing may be kept in perfect workingcondition and the piston-rod effectually lubricated, while at the sametime a perfect seal is provided to thoroughly prevent any escape of gasfrom the pump-cylinder or inlet of air into said cylinder from theexterior.

The arrangement of the inner and outer stuffing-boxes with an oil-sealchamber between them is of particular importance when a vacuum is formedon the low-pressure side of the refrigerating or ice-making apparatus inshutting down the apparatus or blowing out the'expansion-coils. ltiswellknown that in machines employing stuffing-boxes and oil seals ofordinary construction the inlet of air into the chamber, which is avital objection, cannot be avoided, for the reason that the creation ofa vacuum causes a contraction of the stufing-box and a consequent inrushof air.-

Letters Patent filed February 15,1899, Serial No. 705,545, and theoperation thereof is as follows: On the downstroke of the piston theammonia gases and liquids flow into the cylinder through thesuction-port, and the valve f being closed the piston forces the gasesand liquids beneath it past the valve '21 into the chamber 0 and outthrough the dischargeport. On the reverse or up stroke of the piston thevalve f opens to permit the passage of the gases and liquids through thepiston while the valve 6 closes, whereby the gases and liquids pass tothe under side of the piston to take the place of the gases and liquidspreviously expelled by the downstroke of the piston. The gases andliquids on entering drop by gravity onto and through the piston, andthus thoroughly drench and cool the same and cylinder-walls, and owingto the very slight friction created by the piston in its action undueexpansion does not occur and a full load is thereby compressed by thepiston on each working stroke. The location of the suction-port belowthe upper head B of the cylinder also prevents the liquids from cominginto contact with saidhead and as the saturated gases also gravitatedownward only a small proportion of the gases come in contact therewithand these are not unduly expanded, owing to the perfect balancing of thepiston rod, whereby excessive friction is avoided, and to thecounteracting cooling effectof the larger body of gravitating liquidsand gases. Hence the slight amount of heat generatedby the action of thepiston in working and in compressing the gases and liquids is taken upby the liquid ammonia in its expansion into vapor and the use of awaterjacket obviated. Lubrication of the piston is effected by theammonia, which, as is well known, possesses slight lubricatingproperties. Heretofore it has been found necessary to inject oil intothe cylinders of compressors to lubricate the pistons, owing to the highdegree of heat developed; but by employing a compressor in which thepiston operates to compress the ammonia in its downstroke and isperfectly balanced, so as to minimize friction, I am enabled to utilizethe lubricating properties of the ammonia alone and to dispense with theuse of foreign lubricating agents, which have a deleterious effect onthe ammonia and are liable to congeal, gum up, and otherwise interferegreatly with the operation of the pump and other parts of therefrigerating apparatus. The bottom head of the cylinder is maintainedat a low temperature by the action of the liquid and gases fallingthereon between the periods of compression; but superheating of theammonia unavoidably takes place during compression, and it is tocompensate for this that the chamber C is provided. This chamber is, asbefore stated, of the same area in diameter as the cylinder, and theheated gas flowing through the restricted port 2' expands therein and isthereby relieved of a portion of the 4 e idii heat of compression, sothat it will pass'out through the discharge-port O at a temperature butlittle above the boiling-point, due to condenser pressure, whereby but asmall amount of water on the condenser will be required to quicklyrelieve the gas of its heat and liquefy it. The chamber also serves as atrap or receptacle which retains all foreign substances washed downthereinto by the falling gases and liquids and prevents the same frompassing to the condenser and a second time throughout the system.

Refrigerating and ice-making apparatus employinga gas, such as anhydrousammonia, liquefiable under mechanical compression, have hithertooperated under two systemsnamely, the dry or hot gas system and the coldor humid gas system. In machines operating under the dry-gas systemvertical compressors having suction and discharge ports arranged,respectively, at the bottom and top thereof and pistons working tocompress and discharge the gas on the upstroke areinvariably employed.When the bottom thereof and cannot be discharged until it is generatedinto gas by the heat and pounding action of the piston. This poundingaction of the piston tends to force a portion of the liquid ammonia outthrough the stuffing-boxin thebottom head of the cylinder, and hencethere is a loss of ammonia and consequent congelation of the oil usedfor lubrication, and the corresponding increase of friction causesoverheating of the brasses and piston-rod. Choking of thesuction-valves, piston, and other coacting parts of the pump also occursthrough the deposit and accumulation in the bottom of the cylinder ofthe oil, foul gases, scale, and other non-volatile liquid and solidresiduum carried along with the ammonia in its passage through thesystem, and-as this matter cannot be expelled by the piston and if leftto remain quickly gums and cuts the piston and valves to an injuriousextent, frequent dismantling and cleaning of the pump, or blowing out ofthe system by hot air or gases is necessary to keep the pump in workingorder. Furthermore, the stufiingboxes of such pumps must be adjustedvery tightly about the piston-rod to prevent a serious loss of ammoniaby the expulsion of the ammonia upon the downstroke of the piston, and alarge amount of power is required to operate the piston on its workingstroke, as the weight thereof in addition to the resistance tocompression must be overcome by the operating mechanism. The greaterweight of the piston being also at the upper end of the rod, wabbling ofthe piston and excessive friction and unequal wear on the packingringsconstantly occur, thereby causing undue heating and expansion of theammonia. To avoid the formation of a film and loss by clearance upon theupstroke of the piston and knocking out of the lower head of thecylirider upon the downstroke of the piston, careful and constantadjustment of the brasses of the connecting-rod is required, as theleast Wear on said brasses will cause the piston to drop and not goclear to the upper head on its upstroke and to strike the bottom head onits downstroke. In the cold or humid gas system horizontal pumps areemployed, and an excessive amount of friction is created owing to therelatively large area and great weight of the piston which restsdirectly upon the bottom of the cylinder. The piston also constantlyruns in contact with a mass of accumulated residuum, which gravitates tothe bottom of the cylinder, and in consequence becomes quickly cut upand Worn out.

The great advantages of my improved pump having its suction anddischarge ports located, respectively, at the top and bottom of thecylinder and a piston operating to compress the ammonia on itsdownstroke may be stated, in part, as follows: First, the gases andliquids do not come in contact with the top head of the cylinder throughwhich the piston works, and are therefore not unduly expanded uponentering the cylinder; second, less power is required to operate it thaneither of the types of pumps heretofore employed, and less friction iscreated, because the piston hangs plumb, with its greatest Weight at itslower end, and is thereby held perfectly balanced, so that the weight ofthe piston and piston-rod does not rest at any time on the wall or headof the cylinder and the piston cannot wabble or move out of line andbear unequally in either of said parts, and hence the cylinder-walls arenot unduly heated, as the packing-rings only bear thereon, and thefriction created by these alone is practically m'l; third, as expansionpressure only comes on the piston the piston-rod may be run very looselyin its stuffing-box and heating of the upper head of thecylinderprevented; fourth, the entering gases and liquids travel bygravity from the suction-port to the bottom of the cylinder, so that nodrawing or suction action of the piston is required to fill thecylinder; fifth, the falling gases and liquids thoroughly drench andcool the piston and walls of the cylinder and also wash all of theresiduum down to the bottom of the cylinder and into the chamber 0,thereby keeping the cylinder clear of foreign matter and prolonging thelife of the same and the piston; sixth, the

spirit or sacrificing any of the advantages thereof.

Having thus described the invention, what is claimed as new is- 1. In acompression-pump for ice-making and refrigerating apparatus, thecombination of a pump-cylinder having suction and discharge ports and avalved outlet to said discharge-port, a piston comprising a hollowpiston-head shell open-at one end and provided with ports at its otherend, a valve arranged to close against a seat on the open end of theshell, a spider above the valve-seat, a removable cup independent of thevalve-seat and normally supported above the same and inclosed by saidspider, a stem projecting through the cup, a spiral spring inclosedwithin the cup and encompassing the stem, and a nut fitted on the freeend of the stem and arranged so as to bear against and hold the sameconfined within said cup.

2. In a compression-pump for refrigerating and ice-making apparatus, thecombination of a pump-cylinder"having suction and discharge ports and avalve-outlet to said discharge-port, a piston having a hollow pistonheadshell open at one end and provided with ports at its other end, avalve-seat fitted in said open end and provided at its inner end with aspider, a cup on said spider, a valve arranged in said valve-seat andprovided with a stem projecting through said cup, guide-fingers on thevalve arranged about the cup, a coiled spring arranged in the cup aboutthe stem, and a nut fitted on the stem and confining the spring.

3. In a compression-pump for refrigerating and ice-makin g machines, thecombination of a pump-cylinder having a suction-pipe opening into itsupper end and flanged at its lower end, a piston working therein, adetachable lower head bolted to said flange and having a discharge-port,a valve-casing comprising an annular wall formed integrally with andhanging pendent from said head and forming a chamber of approximatelythe same diameter as the cylinder, said wall being provided at its lowerend with an annular flange and at one side with a discharge-pipe ofreduced diameter with respect thereto, a valve arranged to close theport in the lower head and having a depending hollow stem with portstherein, a bottom plate bolted to the flange on the annular wall andclosing said valve-casing and provided with a guide for the valve and astud, and a spring inclosed in the stem of the valve and seated on saidstud.

I. A com pression-pump for refrigerating and ice-making apparatusemploying a gas, such as anhydrous ammonia, liquefiable under mechanicalcompression, comprising a vertical cylinder having a suction-port at itsupper end and a discharge-valve casing at its lower end, said casingbeing of the same diameter as the cylinder and consisting of top andbottom heads or plates and an annular connecting-wall, said top plate ofthe casing being connected to and serving as the bottom head of thecylinder and provided with a port of less diameter than the cylinder andthe annular wall being free from connection with the cylinder and havinga discharge-port of less size than said suction-port and the port .inthe bottom head, a sensitive balanced discharge-valve arranged in saidcasing and also of less diameter than the cylinder and controlling theport in the bottom head and adapted to open solely under the pressure ofthe ammonia under compression, and a piston operating to compress theammonia on its downstroke and having a hollow piston-head shell providedwith a valve-seat having a port of less diameter than the bore of theshell and a balanced valve closing upwardly against said seat,substantially as described.

In testimony whereof I affix my signature in presence of two witnesses.

GEORGE B. HIETT.

Witnesses:

JAS. W. AUSTIN, A. L. HOLTON.

